An unusual type of fracture in the upper sacrum.

An unusual type of indirect isolated fracture of the upper sacrum is presented. The upper sacrum was markedly comminuted and nondisplaced relative to the lower fragment. There was a neurologic deficit present. On the basis of a review of the literature, a previous classification system and the actual fracture mechanism, this fracture is classified as a special type; type 4, or the neutral position fracture.